Tone wheel built-in constant velocity joint

ABSTRACT

A rolling bearing unit has a hub which is formed with a housing for partly forming a constant velocity joint, wherein a connecting tube 20 of a magnetic metal plate is provided to have a base half portion 21 fitted onto the opening portion of the housing and a tip half portion 22 projecting from the housing, and a number of through holes 26 are formed in an axial portion of the base half portion and arranged circumferentially to function as a tone wheel.

FIELD OF THE INVENTION

The present invention relates to a tone wheel built-in constant velocityjoint for transmitting rotational force to a driven wheel such as therear wheel of the FR vehicle (front engine rear wheel drive vehicle) orthe RR vehicle (rear engine rear wheel drive vehicle), the front wheelof the FF vehicle (front engine front wheel drive vehicle), and thewhole wheels of the 4WD vehicle (four wheel drive vehicle), whiledetecting the rotational speed of the driven wheel.

BACKGROUND OF THE INVENTION

The constant velocity joint is used to transmit the rotational forcetaken out of the engine through the transmission.

JP Patent Publication KOKAI NO. H7-317754 discloses a conventionalrolling bearing unit for vehicle wheel having a constant velocity joint,where the constant velocity joint is combined with the rolling bearingunit, so that the driven wheel is rotatably supported by the suspensionwhile the rotational force is transmitted to the driven wheel.

FIG. 8 shows the conventional structure disclosed in this publication.An outer ring or race 1 is supported by the suspension so as not torotate when incorporated in the vehicle, and formed with a first mountflange 2 on its outer peripheral surface to be supported by thesuspension and with outer ring raceways 3 in double rows on its innerperipheral surface. A hub 4 is provided on the radially inside of theouter ring 1, and formed with a second mount flange 5 on its outerperipheral surface at the axially outer end (left end in the drawings)to support a vehicle wheel (not shown), with inner ring raceways 6 indouble rows on its outer peripheral surface at the axially middleportion, and with a housing 8 for the constant velocity joint 7 at theaxially inner end (right end in the drawings). A plurality of rollingmembers 9 are provided between the outer ring raceways 3 and the innerring raceways 6 to rotatably support the hub 4 inside the outer ring 1.

The terms "axially outer" and "axially outside" mean the widthwiseoutside when installed in the vehicle while the terms "axially inner"and "axially inside" mean the widthwise inside when installed in thevehicle in the present specification.

Substantially cylindrical covers 10 made of a metal plate such asstainless steel and annular seal rings 11 made of elastic member such aselastomer e.g. rubber are provided between the opposite opening portionsof the outer ring 1 and the outer peripheral surface at the middleportion of the hub 4. The covers 10 and seal rings 11 isolate theportion where the rolling members 9 are located, from outside, andprevent the grease in this portion from leaking out to the outside, andthe foreign matter such as rain water, dust from entering this portion.

The constant velocity joint 7 comprises, in addition to the housing 8,an inner ring or inner joint member 12 and balls 13, which are arotation or torque transmitting member, respectively. The balls 13 arerotatably supported by a cage 14. Engaged in a spline joint with theinside of the inner ring 12 is the end of the drive shaft (not shown)which is rotated through the transmission by the engine.

Formed on the outer peripheral surface of the inner ring 12 are aplurality of (e.g. six) inner engagement grooves 15 in arcuate crosssection which are circumferentially arranged with a uniform interval toextend at right angles with reference to the circumferential direction.

Formed on the inner peripheral surface of the housing 8 facing the innerengagement grooves 15 are a plurality of outer engagement grooves 16 inarcuate cross section which are circumferentially arranged to extend atright angles with reference to the circumferential direction.

The balls 13 can roll along the inner and outer engagement grooves 15,16 when supported by the pockets 17 of the cage 14, respectively.

When installing into the vehicle the rolling bearing unit integral withthe constant velocity joint as constructed above, the outer ring 1 issupported by the suspension through the first mount flange 2 while forexample the front wheel, that is a driven wheel, is connected to the hub4 through the second mount flange 5. The end portion of the drive shaft(not shown) is engaged in a spline joint with the inside of the innerring 12 of the constant velocity joint to be rotatably driven by theengine through the transmission.

When the vehicle is moving, the rotation of the inner ring 12 istransmitted to the hub 4 through the balls 13 to rotate the drivenwheel, e.g. front wheel.

There is a problem that the conventional rolling bearing unit forvehicle wheel as shown in FIG. 8 is hard to make the unit compact andlightweight. The reason is as follows;

In the constant velocity joint 7 integrally combined with the rollingbearing unit, six inner engagement grooves 15, six outer engagementgrooves 16 and six balls 13 are used. In this case, in order to transmitthe required torque keeping the rolling fatigue life of the innerengagement grooves 15 and outer engagement grooves 16 and of the rollingcontact surfaces of the balls 13 of the constant velocity joint, theouter diameter of the balls 13 of the constant velocity joint 7 must belarge in a degree. Accordingly, in the conventional rolling bearing unitfor the vehicle wheel, the diameter of the circumscribing circle of theouter engagement grooves 16 determined by the size of the diameter ofthe circumscribing circle of the balls 13 is larger than the diameter ofthe inner ring raceways 6 on the outer peripheral surface at the middleportion of the hub 4.

Therefore, in the conventional rolling bearing unit for the vehiclewheel, the rolling bearing section comprising the outer ring 1, hub 4and rolling members 9 and the section of the constant velocity joint 7are arranged in series in the axial direction as shown in FIG. 8.However, in this series arrangement, the whole axial size of the rollingbearing unit for the vehicle wheel is larger, and by that amount, thewhole apparatus weight is larger. The weight increase of the rollingbearing unit increases the unspring weight of the vehicle, which wouldworsen the ride comfortability and fuel consumption performance.Therefore, making the rolling bearing unit for the vehicle wheel compactand lightweight is required.

Under such a situation, the present inventors invented the rollingbearing unit for the vehicle wheel combined with the constant velocityjoint disclosed in JP Patent Application No. H9-191433.

In the rolling bearing unit for the vehicle wheel combined with theconstant velocity joint of this patent application, as shown in FIG. 9,the number of the inner engagement grooves 15 on the outer peripheralsurface of the inner ring or inner joint member 12, the outer engagementgrooves 16 on the inner peripheral surface of the housing 8a of theconstant velocity joint 7a, which is provided on the axially inner endof the hub 4a, and the balls 13 between the inner and outer engagementgrooves 15 and 16 are seven or more (e.g. 8-12), respectively, so thatthe load applied to the balls 13 during use of the rolling bearing unitis smaller than in the conventional structure. By that amount, the outerdiameter of the balls 13 is made smaller, so that the diameter of thecircumscribing circle of the balls 13 arranged in an annular shape, andthe diameter of the circumscribing circle of the outer engagementgrooves 16 are made smaller than the diameter of at least the axiallyinside one of the inner ring raceways 6 which are formed on the outerperipheral surface of the middle portion of the hub 4a. In addition, theaxially inside one of the inner ring raceways 6 is made to overlap part(the left part in FIG. 9) of the outer engagement grooves 16 in theradial direction.

The operation to rotatably support the vehicle wheel to the suspensionby the rolling bearing unit of this application is substantially thesame to that of the conventional rolling bearing unit as mentionedabove.

Particularly, in the case of the rolling bearing unit of this patentapplication, the diameter of the circumscribing circle of the outerengagement grooves 16 is smaller than the diameter of the axially insideone of the inner ring raceways 6, so that this inner ring raceway 6 ismade to radially overlap part of the outer engagement grooves 16.Accordingly, by this overlap amount, the axial size of the rollingbearing unit for the vehicle wheel is made smaller so as to make thewhole apparatus compact and lightweight.

However, it is difficult to incorporate in the structure of FIG. 9 thetone wheel for detecting the rotational speed of the vehicle wheel.Specifically, detecting the rotational speed of the vehicle wheel isrequired to control the antilock brake system (ABS) and the tractioncontrol system (TCS). And, the tone wheel with the circumferentialproperty changed alternately with a uniform interval must be fixedlysupported on the inside of the first mount flange 2 on part of the hub4a rotating with the vehicle wheel in order to detect the rotationalspeed.

However, in the case of the patent application of FIG. 9, the inner ringraceway 6 on the axially inside is made to radially overlap part of theouter engagement grooves 16 to reduce the axial size of the rollingbearing unit, which reduces the axial size L₁₈ of the axially inner endportion 18 axially inwardly projecting from the seal ring 11 at theaxially inner end of the housing 8a adjacent the axially inner endportion of the hub 4a.

Fitted onto the axially inner end portion 18 is the axially outer endportion of the boot (not shown) which shields the interior of thehousing 8a from outside to prevent the foreign matter from entering thehousing 8a while preventing the grease in the housing 8a from leakingout. In addition, the axially outer end of the boot must be retained onthe outer peripheral surface at the axially inner end portion of thehousing 8a with a retaining band (not shown). For the rolling bearingunit combined with the constant velocity joint improved as shown in FIG.9, the space for incorporating the tone wheel is not available so longas any modification is made.

SUMMARY OF THE INVENTION

Under such situation, an object of the present invention is to provide aconstant velocity joint wherein a tone wheel can be incorporated in itto detect the rotational speed of the vehicle wheel even if there is nospace available to incorporate an independent tone wheel in the rollingbearing unit for the vehicle wheel integral with the constant velocityjoint improved as mentioned above.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional view of a first example of the embodimentsof the constant velocity joint according to the present invention.

FIG. 2 is a cross sectional view of a second example of the embodimentsof the constant velocity joint according to the present invention.

FIG. 3 is a cross sectional view of a third example of the embodimentsof part of the constant velocity joint according to the presentinvention.

FIG. 4 is a cross sectional view of a fourth example of the embodimentsof the constant velocity joint according to the present invention.

FIG. 5 is a cross sectional view of a fifth example of the embodimentsof the constant velocity joint according to the present invention.

FIG. 6 is a cross sectional view of a sixth example of the embodimentsof the constant velocity joint according to the present invention.

FIG. 7 is a cross sectional view of a seventh example of the embodimentsof the constant velocity joint according to the present invention.

FIG. 8 is a cross sectional view of an example of the conventionalstructures.

FIG. 9 is a cross sectional view of an example of the embodiments in JPPatent Application No. H9-191433.

PREFERRED EMBODIMENTS OF THE PRESENT INVENTION

The tone wheel built-in constant velocity joint of the present inventioncomprises a housing having an inner peripheral surface formed with anaxially long engagement grooves or recesses, a rotational shaft insertedinto the interior of the housing, and a rotation or torque transmissionmember provided between the outer peripheral surface of the rotationalshaft and the engagement grooves or recesses of the housing.

The tone wheel built-in constant velocity joint in a first feature isequipped with a connecting tube having a base half portion fixedlyfitted onto the opening end portion of the housing and a tip halfportion axially projecting from the opening end face of the housing, anda boot made of a resilient material and having one end fixedly fittedonto the tip end portion of the connecting tube. In addition, theconnecting tube has a detected portion to be the tone wheel having acircumferential property alternately changing with a uniform interval.

The tone wheel built-in constant velocity joint in a second feature isequipped with a connecting tube fixedly fitted onto the opening endportion of the housing, and a boot made of a resilient material andhaving one end fixedly fitted onto part of the connecting tube. Inaddition, the connecting tube has another part projecting from the boot,and the another part is provided with a detected portion for the tonewheel having a circumferential property alternately changing with auniform interval.

The tone wheel built-in constant velocity joint in a third feature isequipped with an inner ring fixedly fitted onto the middle portion ofthe housing to partly form the rolling bearing unit, and a boot made ofa resilient material and having one end fixedly fitted onto an endportion of the housing, the housing having an anchoring groove on theouter peripheral surface thereof axially between the end edge portion ofthe boot and the inner ring, a stop ring engaged with the anchoringgroove to prevent the inner ring from being displaced with reference tothe housing, and a retaining ring fixedly fitted onto the stop ring, andpart of the retaining ring having a detected portion to be the tonewheel having a circumferential property alternately changing with auniform interval.

The tone wheel built-in constant velocity joint in a fourth feature isequipped with an inner ring fixedly fitted onto the middle portion ofthe housing to partly form the rolling bearing unit, and a boot made ofa resilient material and having one end fixedly fitted onto an endportion of the housing, the housing having an anchoring groove on theouter peripheral surface thereof axially between the end edge portion ofthe boot and the inner ring, a stop ring engaged with the anchoringgroove to prevent the inner ring from being displaced with reference tothe housing, and a tone wheel being integral with the housing or fixedlyconnected directly or through another member to part of the housing torotate with the housing, and the tone wheel formed with a portion to bea detected portion having a circumferential property alternatelychanging with a uniform interval and the portion placed in the spacesurrounded by the outer peripheral surface of the stop ring, the outerperipheral surface of the boot, the inner peripheral surface of themount hole in the knuckle for fixing the outer ring of the rollingbearing unit.

In operation, since e.g. the connecting tube for connecting one end ofthe boot to the opening end portion of the housing, or the retainingring for fixing the stop ring to the housing are used as a tone wheel inthe tone wheel built-in constant velocity joint of the present inventionconstructed as mentioned above, there is no need of the space for anindependent tone wheel to be incorporated therein. Accordingly, even ifno space is available for an independent tone wheel to be incorporatedtherein, it is possible to detect the rotational speed of the vehiclewheel. In addition, the connecting tube or the retaining ring takes therole of the tone wheel, the number of parts is not increased, and therein no cost increase of the constant velocity joint due to the tone wheelincorporated therein.

Now, embodiments of the present invention are explained with referenceto the drawings.

FIG. 1 shows a first example of the embodiments of the present inventioncorresponding to the first feature.

The outer ring 1 is made of a metal member such as carbon steel andformed in a single piece through a forging process and being supportedby the suspension so as not to be rotated during use. Specifically, theouter ring 1 has an outer peripheral surface formed with a first mountflange 2 to be supported by the suspension and an inner peripheralsurface formed with outer ring raceways 3 in double rows.

The hub 4b is provided on the radially inside of the outer ring 1 andmade of a metal member formed in a single piece through a forgingprocess. Specifically, the hub 4b has an outer peripheral surface whichis, at its axially outer end, formed with a second mount flange 5 tosupport a vehicle wheel and, at its middle portion, inner ring raceways6 in double rows. The inner half portion of the hub 4 forms a housing 8bfor the constant velocity joint 7. A plurality of rolling members 9 areprovided between the outer ring raceways 3 and the inner ring raceways 6to rotatably support the hub 4b inside the outer ring 1.

Provided between the inner peripheral surface at either end of the outerring 1 and the outer peripheral surface at the middle portion of the hub4b is a seal ring assembly 19 which comprises a slinger and a seal ringto isolate from the outside the portion where the rolling members 9 arelocated and to prevent the grease from the portion to the outside and toprevent the foreign matter such as rain water, dust from entering theportion from the outside.

The constant velocity joint 7 is equipped, in addition to the housing8b, with an inner ring or inner joint member 12 and a plurality of balls(see FIG. 2, FIGS. 4 to 9, omitted in FIG. 1), which are a rotation ortorque transmission member, respectively. The balls 13 arereciprocatively rotatably supported in the cage 14 (FIGS. 2, 4, 5, 8 and9). Engaged with the inside of the inner ring 12 through a spline jointis an end of the driving shaft (not shown) which is rotatably driven bythe engine through the transmission. Formed on the outer peripheralsurface of the inner ring or inner joint member 12 are a plurality (e.g.eight) of inner engagement grooves 15 (FIGS. 2, 4, 5, 8 and 9) which hasan arcuate shape in cross section and are arranged circumferentiallywith a uniform interval, each extending in an orthogonal direction tothe circumferential direction.

At the portion on the inner peripheral surface of the housing 8b facingthe inner engagement grooves 15, outer engagement grooves 16 in arcuateshape in cross section extend in an orthogonal direction to thecircumferential direction, respectively. The balls 13 are held in thepockets 17 (FIGS. 2, 4, 5, 8 and 9) of the cage 14, respectively, and inthis state, rotatable along the inner and outer engagement grooves 15,16.

Fitted onto the opening portion at the axially inner end of the hub 4bintegral with the housing 8b is the base half portion 21 of theconnecting tube 20 which is made of a magnetic metal plate havingcorrosion resistance, such as stainless steel, e.g. SUS 430, galvanizedplate steel plate. The connecting tube 20 is generally formed in acylindrical shape with a crank shape in cross section, wherein the basehalf portion 21, larger in diameter, is connected to the tip halfportion 22, smaller in diameter, through the step portion 23. When thestep portion 23 of the connecting tube 20 is abutted to the axiallyinner end face of the hub 4b, the tip end edge of the base half portion21 is fixed to the axially inner end of the hub 4b, specifically in theanchoring groove 24 formed on an outer peripheral surface portion of thehub 4b closer to axially its inner end, by way of crimping such asrolling processing.

Provided between the inner peripheral surface of the base half portion21 and the outer peripheral surface at the axially inner end of the hub4b is an O-ring 25 which prevents the rain water etc. from entering thehousing 8b through between the peripheral surfaces.

In the state of incorporation into a vehicle, the axially outer endportion of the boot 27 is fitted onto the tip half portion 22 of theconnecting tube 20 for being dust tight and water tight.

The boot 27 is made in a single piece by an resilient member such aselastomer e.g. rubber, synthetic resin, and comprises an intermediatebellows portion, and opposite cylindrical end portions. The axiallyouter end portion of the boot 27 forms a connecting tube portion 28.

The connecting tube portion 28 provided on the axially outer end of theboot 27 is fitted onto the tip half portion 22 of the connecting tube20, and the outer peripheral surface of the axially outer end of theboot 27 is retained by the retaining band 29.

Provided on the outer peripheral surface of the middle portion of thetip half portion 22 is a groove 30 or projection for engagement with theinner peripheral surface of the connecting tube portion 28 of the boot27 to prevent the outer end portion of the boot 27 from being taken outfrom the tip half portion 22.

Formed on an axial portion of the base half portion 21 of the connectingtube 20, closer to the axially outside than the portion facing theO-ring 25, are a number of slit-shaped through holes 26 which are longin the axial direction, and arranged circumferentially with a uniforminterval to be used as a detected portion.

The magnetic property of the axial portion, that is the detectedportion, of the base half portion 21 changes circumferentiallyalternately with a uniform interval. Thus, in the rolling bearing unitintegral with the tone wheel built-in constant velocity joint, the axialportion of the base half portion 21 formed with the through holes 26 isused as the tone wheel.

When incorporating the rolling bearing unit integral with the tone wheelbuilt-in constant velocity joint for the vehicle wheel, the outer ring 1is supported to the suspension through the first mount flange 2, and thedriven wheel, e.g. front wheel, is connected to the hub 4b through thesecond mount flange 5. The tip end of the driving shaft (not shown),rotatably driven through the transmission by the engine, is connected tothe interior of the inner ring 12 of the constant velocity joint with aspline engagement. When the vehicle is moved, the rotation of the innerring 12 is transmitted to the hub 4b through the balls 13 to rotate thefront wheel.

The sensor 31 is supported by the fixed portion such as the knuckle 57of the suspension and formed with a detecting portion on its tip end,which faces through a clearance the outer peripheral portion of theaxial portion with the through holes 26 of the base half portion 21.When moving the vehicle, as the hub 4b rotates, the through holes 26 andthe column portions of magnetic material between the circumferentiallyadjacent through holes 26 alternately pass by the detecting portion ofthe sensor 31. Consequently, the amount of magnetic flux through thesensor 31 changes, and the output of the sensor 31 changes. Thefrequency at which the output of the sensor 31 changes is proportionalto the rotational speed of the hub 4b, and by sending the output of thesensor 31 to a control device (not shown), the rotational speed of thehub 4b rotating with the vehicle wheel is obtained to control the ABSand TCS.

In the rolling bearing unit integral with the tone wheel built-inconstant velocity joint, the axially outer end of the boot 27 isconnected to the opening portion of the axially inner end of the housing8b in the axially inner half portion of the hub 4b by way of theconnecting tube 20 which is used as the tone wheel, so that no space isrequired to incorporate an independent tone wheel. Accordingly, it ispossible to detect the rotational speed of the vehicle wheel even ifthere is no space secured to incorporate the independent tone wheel.

In addition, since the connecting tube 20 takes the role of the tonewheel, the number of parts, and the cost of the rolling bearing unit arenot increased by combining it with the tone wheel built-in constantvelocity joint.

FIG. 2 shows a second example of the embodiments of the presentinvention corresponding to the second and fourth features.

The outer ring 1 has an inner peripheral surface which is formed withthe outer ring raceways 3a, 3b in double rows, and the hub 4c isprovided on the inner diameter side of the outer ring 1. The hub 4ccomprises a hub element 32 and an inner ring 33 fitted on the hubelement 32 in a concentric relationship with the outer ring 1. Innerring raceways 6a, 6b are disposed on the outer peripheral surface of thehub 4c at a portion facing the outer ring raceways 3a, 3b.

The inner ring raceway 6a on the axially outer side (left side in FIG.2) is directly formed on the outer peripheral surface at the middleportion of the hub element 32.

The inner ring 33 is fitted onto a portion of the middle portion of thehub element 32 closer to the axially inner end (right side in FIG. 2)than the inner ring raceway 6a on the axially outer side. The inner ringraceway 6b on the axially inner side (right side in FIG. 2) is formed onthe outer peripheral surface of the inner ring 33.

The rolling members 9 are rotatably provided between the outer ringraceways 3a, 3b and the inner ring raceways 6a, 6b to rotatably supportthe hub 4c on the radially inside of the outer ring 1.

In the example illustrated, since the inner ring raceway 6a on theaxially outer side is directly formed on the outer peripheral surface ofthe hub element 32, the diameter of the inner ring raceway 6a on theaxially outer side is smaller than the diameter of the inner ringraceway 6b on the axially inner side formed on the outer peripheralsurface of the inner ring 33.

In addition, since the diameter of the inner ring raceways 6a on theaxially outer side is smaller than the diameter of the inner ringraceway 6b on the axially inner side, the diameter of the outer ringraceway 3a on the axially outer side facing the inner ring raceway 6a onthe axially outer side is smaller than the diameter of the outer ringraceway 3b on the axially inner side.

The outer diameter of the outer half portion (left half portion in FIG.2) with the outer ring raceway 3a of the outer ring 1 is smaller thanthe outer diameter of the inner half portion (right half portion in FIG.2) with the outer ring raceway 3b of the outer ring 1.

In the example illustrated, since the diameters of the inner ringraceway 6a and outer ring raceway 3a on the axially outer side are madesmaller, the number of rolling members 9 between the inner ring raceway6a and the outer ring raceway 3a on the axially outer side is smallerthan the number of rolling members 9 between the inner ring raceway 6band the outer ring raceways 3b on the axially inner side.

Since the diameter of the pitch circle of the rolling members 9 in theaxially outer row of rolling members is smaller, the outer diameter ofthe outer half portion of the outer ring 1 is smaller. By that amount,the diameter of the pitch circle of the studs 34 fixed to the secondmount flange 5 on the outer peripheral surface of the hub element 32 issmaller. Accordingly, without increasing the axial size of the hubelement 32, the outer diameter of the second mount flange 5 with thestuds 34 fixed thereto is smaller, thereby effectively making therolling bearing unit for the vehicle wheel lightweight and compact.

As the pitch circle diameter of the rolling members 9 in the axiallyouter row of rolling members is smaller than the pitch circle diameterof the rolling members 9 in the axially inner row of rolling members,the basic dynamic load rating of the axially outer row of rollingmembers is smaller than that of the axially inner row of rollingmembers. Accordingly, if the same load is applied to the both rows, thelife of the axially outer row of rolling members is shorter than that ofthe axially inner row of rolling members.

Since the load applied to the axially outer row of rolling members issmaller than the load applied to the axially inner row of rollingmembers in generally used automobile. Accordingly, the design forsubstantially equalizing the both rows in life is easily achieved,excluding too short life of each part.

The second mount flange 5 for fixedly supporting the vehicle wheel withthe hub element 32 is integrally provided on the outer peripheralsurface of the axially outer end of the hub element 32. The studs 34 forsecuring the vehicle wheel have their base end portions fixed to thesecond mount flange 5. In the example illustrated, the pitch circlediameter of the studs 34 is made smaller by the amount that the outerdiameter of the axially outer half portion of the outer ring 1 issmaller than the outer diameter of the axially inner half portion of theouter ring 1, preventing interference between the head 35 of the studs34 and the outer peripheral surface of the axially outer end of theouter ring 1.

With the outer peripheral surface of the hub element 32, the diameter ata portion axially inner than the inner ring raceway 6a on the axiallyouter side is smaller than the diameter of the inscribing circle of therolling elements 9 mating with the inner ring raceway 6a. This isbecause, upon assembling the rolling bearing unit, the hub element 32can be inserted into the outer ring 1 in the state where the seal ring11 is fixedly fitted into the inner peripheral surface of the axiallyouter end of the outer ring 1 while the rolling members 9 areincorporated on the inner diameter side of the outer ring raceway 3a onthe axially outer end of the outer ring 1.

With the outer peripheral surface at the middle portion of the hubelement 32, the portion between the inner ring raceway 6a on the axiallyouter side and the portion where the inner ring 33 is fitted, is formedwith circumferentially a recessed groove portion 37 to reduce the weightof the hub element 32.

In order to prevent the inner ring 33 on the hub element 32 from movingtoward the axially inner end, and in order to keep the preload at aproper value on the rolling members 9 provided rotatably between theouter ring raceways 3a, 3b and the first and second inner ring raceways6a, 6b, the stop ring 39 is secured in the anchoring groove 38circumferentially formed generally on the outer peripheral surface ofthe hub element 32 at a portion closer to the axially inner end.

The stop ring 39 comprises a pair of stop ring elements each formed in asemi circular shape.

The stop rings 39 have an inner peripheral edge portion engaged with theanchoring grooves 38 to provide the rolling members 9 with a properpreload, by pressing the inner ring 33 axially outward with reference tothe hub element 32. In order that even when the force thus pressing theinner ring 33 is released, the proper preload is kept onto the rollingmembers 9, the stop ring 39 in a proper thickness is selected for use.Specifically, a various kinds of stop rings 39 with slightly differentin thickness are prepared, and the stop ring 39 with the most properthickness is selected with respect to the groove width etc. of theanchoring groove 38, dimensions of the parts of the rolling bearingunit, for engagement of the anchoring grooves 38. Accordingly, byengaging the stop ring 39 with the anchoring groove 38, after thepressing force is released, the inner ring 33 is prevented from movingtoward the axially inner end, and the proper preload is kept to beapplied to the rolling members 9.

In order to prevent the pair of stopping elements of the stop ring 39from moving radially outward by centrifugal force and to prevent thestop ring 39 from being erroneously taken off from the anchoring groove38, part of the connecting tube 20a is provided around the stop ring 39.The connecting tube 20a is provided to fittingly support the outer endof the boot 27 which is provided to prevent the foreign matter such asrain water, dust from entering the constant velocity joint 7b comprisingthe housing 8c on the axially inner end of the hub element 32. The outerend of the boot 27 is fitted onto the fitting tube portion 41 of theconnecting tube 20a fixedly fitted onto the axially inner end of the hubelement 32 through interference, and retained on the outer peripheralsurface of the fitting tube portion 41 by the retaining band 29.

On the outer peripheral surface at the axially middle portion of thefitting tube portion 41, the engagement projection 42 iscircumferentially formed, and engaged with the engagement groove 43formed circumferentially on the inner peripheral surface of the outerend of the boot 27, so that the axially outer end of the boot 27 isprevented from being pulled out of the fitting tube portion 41.

The connecting tube 20a is made of a magnetic metal plate such as carbonsteel e.g. SPCC, and formed through a drawing process in a generallyannular shape with crank shaped cross section, and the surface isproperly subjected to the corrosion prevention treatment.

The axially outer end of the fitting tube portion 41 has an edge portionwith L-shaped cross section axially outwardly projected than the boot27, to generally circumferentially form a retaining portion 44.

The retaining portion 44 comprises a circular ring portion 45 bentradially outward at the axially outer end edge of the fitting tubeportion 41 and a retaining tube portion 46 bent axially outward at theouter peripheral edge of the circular ring portion 45. The axiallyoutside surface of the circular ring portion 45 is placed in contactwith or faced closely to the axially inside surface of the stop ring 39,and the inner peripheral surface of the retaining tube 46 is placed incontact with or faced closely to the outer peripheral surface of thestop ring 39.

On the axially outer end edge of the retaining tube 46, a radially outercircular ring portion 47 is formed to extend radially outward through abent portion. A number of slit-shaped through holes 26a, each long in adiameter direction, are circumferentially formed with a uniform intervalin the circular ring portion 47 such that the magnetic property of thecircular ring portion 47 changes circumferentially alternately with auniform interval to provide a detected portion functioning as the tonewheel.

The detecting portion of the sensor 31a faces closely to the inside ofthe circular ring portion 47, and is supported by the stationary portionof the suspension.

In order that the magnetic property of the axially inside surface of thecircular ring portion 47 changes alternately with the uniform interval,a permanent magnet such as rubber magnet can be used instead of thethrough holes 26a, such that the permanent magnet is attached to theaxially inside surface of the circular ring portion 47 with the S-polesand N-poles alternately arranged circumferentially with a uniforminterval.

In the example illustrated, the circular ring portion 47 for thedetected portion functioning as the tone wheel, is disposed in the space59 defined by the outer peripheral surface of the stop ring 39 and theouter peripheral surface of the connecting tube portion 28 at the end ofthe boot 27, the inner peripheral surface of the mount hole 58 of theknuckle 57 for fixing the outer ring 1 of the rolling bearing unit andthe axially inner end surface of the outer ring 1, such that thecircular ring portion 47 does not project from the space 59.Accordingly, the sensor 31a can be fixedly supported by the knuckle 57,and the limited space can be effectively utilized. The other structureand function are substantially the same to those of the first example.Therefore, redundant explanation is omitted, and like members areindicated by like reference numbers.

FIG. 3 shows a third example of the embodiment of the present inventioncorresponding to the second and fourth features, where an engagementgroove 48 is formed in the axially middle portion of the outerperipheral surface of the fitting tube portion 41a of the connectingtube 20b.

The engagement groove 48 is engaged with the engagement projection 49 onthe inner peripheral surface of the connecting tube portion 28 at theaxially outer end of the boot 27 to prevent the connecting tube portion28 of the boot 27 from being taken off from the fitting tube portion41a. The other structure and function are substantially the same tothose of the second example.

FIG. 4 illustrates a fourth example of the embodiments of the presentinvention corresponding to the third and fourth features, where aretaining ring 50 is fixedly fitted onto the stop ring 39 in theanchoring groove 38 of the hub element 32 through interference fit toform the hub 4c.

The retaining ring 50 is made of a magnetic metal plate such as carbonsteel, e.g. SPCC, and formed through a burring process to comprise afitting tube portion 51 and a circular ring portion 52 bent at one endedge of the fitting tube portion 51 at right angles radially outward,such that the retaining ring 50 is formed in an generally annular shapewith L-shaped cross section, and its surface is subjected to corrosionprevention treatment. The fitting tube portion 51 is fixed onto the stopring 39 through interference fit, so that the stop ring 39 comprisingtwo halves is prevented from being taken off from the anchoring groove38 and to support the retaining ring 50 with respect to the housing 8c.

On the other hand, the circular ring portion 52 is formed with a numberof slit-shaped through holes 26a, each being long in a diametricaldirection, circumferentially with a uniform interval, so that themagnetic property of the circular ring portion 52 changescircumferentially alternately with a uniform interval, and that thecircular ring portion 52 is a detected portion functioning as the tonewheel.

The sensor 31a is supported by the stationary portion such as knuckle 57of the suspension, so that the detecting portion of the sensor 31a facesclosely to the axially inside surface of the circular ring portion 52.

In the present example, the connecting tube portion 28 is formed on theaxially outer end of the boot 27 to prevent the foreign matter fromentering the constant velocity joint 7b, and directly fitted onto theaxially inner end of the housing 8c.

In this condition, the projection 53 formed on the inner peripheralsurface of the connecting tube portion 28 is engaged with the groove 30formed on the outer peripheral surface at the axially inner end of thehousing 8c to prevent the connecting tube portion 28 from being pulledoff the housing 8c. The other structure and function are the same tothose of the second example.

FIG. 5 shows a fifth example of the embodiments of the present inventioncorresponding to the third and fourth features, where the retaining ring50a is formed in a crank shape in cross section and comprised of alarger cylindrical portion 54 and a smaller cylindrical portion 55continued to the larger cylindrical portion 54 through a step portion 56to prevent the stop ring 39 from being pulled off from the groove 38.

The smaller cylindrical portion 55 is fixedly fitted onto the stop ring39 by way of interference fit, so that the stop ring 39 comprising twohalves of stop ring elements is prevented from being pulled off from thegroove 38, and to fixedly support the retaining ring 50a with referenceto the housing 8c.

On the other hand, a number of slit-shaped through holes 26, eachaxially long (in the left and right directions in FIG. 5), are formed onthe larger cylindrical portion 54 circumferentially with a uniforminterval, so that the magnetic property of the larger cylindricalportion 54 changes circumferentially alternately with a uniforminterval, so that the larger cylindrical portion 54 is a detectedportion functioning as the tone wheel.

The sensor 31 is supported by the stationary portion such as knuckle 57of the suspension, and the detecting portion of the sensor 31 facesclosely to the outer peripheral surface of the larger cylindricalportion 54. The other structure and function are substantially the sameto those of the fourth example.

FIG. 6 shows a sixth example of the embodiments of the present inventioncorresponding to the third and fourth features, where the retaining ring50b provided to prevent the stop ring 39 from being pulled off from thegroove 38 is used as the cylindrical tone wheel. Specifically, thecylindrical retaining ring 50b is formed with a number of slit-shapedthrough holes 26, each axially long (in the left and right directions inFIG. 6), circumferentially alternately with a uniform interval, so thatthe outer peripheral surface of the retaining ring 50b is a detectedportion functioning as the tone wheel. The sensor 31 is supported by thestationary portion such as knuckle 57 of the suspension, and thedetecting portion of the sensor 31 faces closely to the outer peripheralsurface of the retaining ring 50b. The other structure and function aresubstantially the same to those of the fifth example.

FIG. 7 shows a seventh example of the embodiments of the presentinvention corresponding to the third and fourth features, where theretaining ring 50c is provided to prevent the stop ring 39 from beingpulled off from the groove 38, and the tone wheel 60 that is a circularring shaped permanent magnet is attached to the retaining ring 50c,which is made of a magnetic metal plate and formed, through a burringprocess, in a generally annular shape with L-shaped cross section, andcomprised of a cylindrical portion 61 and a circular ring portion 62extending radially outward from the axially outer end of the cylindricalportion 61. The cylindrical portion 61 is fitted onto the stop ring 39through interference fit, so that the retaining ring 50c is fixedlysupported on the periphery of the stop ring 39, and that the stop ring39 is prevented from being pulled off from the groove 38.

On the other hand, the tone wheel 60 is attached generallycircumferentially to the axially inside surface of the circular ringportion 62 of the retaining ring 50c by way of seizure, adhesion,magnetic attraction force etc.

For example, the tone wheel 60 is made from a rubber magnet with ferritepowders mixed into rubber and axially magnetized (left and rightdirections in FIG. 7). The magnetizing directions are alternatelychanged with a uniform interval in the circumferential direction.Accordingly, N-poles and S-poles are alternately arranged in thecircumferential direction with a uniform interval on the axially insidesurface of the tone wheel 60.

The sensor 31a is provided in the knuckle 57 to project from the innerperipheral surface of the mount hole 58 for fixing the outer ring 1 ofthe rolling bearing unit, and the tip end of the sensor 31a is formedwith the detecting portion, which faces the axially inside surface ofthe tone wheel 60 through a clearance in the axial direction so as toform the sensor unit to detect the rotational speed of the vehicle wheelwhich rotates with the hub 4d.

In order to secure the output of the sensor 31a, the height size W₆₀ inthe diametrical direction of the tone wheel 60 is made larger todesirably increase the amount of magnetic flux from the tone wheel 60.In this example, the retaining ring 50c is fixedly fitted onto the stopring 39 which is smaller in diameter than the inner ring 33, andtherefore the height size W₆₀ is easily secured. Specifically, forexample, the axially inside surface of the slinger 63 fixedly fittedonto the axially inner end of the inner ring 33 to form the seal ringassembly 19 can be used as the portion to support the annular tone wheel60, and in the structure of the present example, the height size W₆₀ canbe made larger comparing with the case where the slinger 63 is providedwith the encoder. In addition, different from the case where the encoderis mounted to the slinger, the diameter of encoder can be freely madelarge. Since the diameter of encoder is proportional to the pole widthin the circumferential direction, the pole width can be made larger byenlarging the diameter, so that the magnetic flux is increased.

In the present example, the hub 4d is formed in a hollow cylindricalshape to communicate the axial opposite ends with each other to make therolling bearing unit for the vehicle wheel lightweight. The shield plate64 is fixedly fitted into the inner peripheral surface at the middleportion of the hub 4b to isolate the communication between the axiallyinner end opening portion and the axially outer end opening portion ofthe hub 4d. The shield plate 64 prevents the foreign matter such as rainwater and dust etc. on the outside from entering the constant velocityjoint at the inner end of the hub 4d, and to prevent the grease in theconstant velocity joint from leaking out to the outside. In order toeffectively prevent the grease from moving from the required portion andto reduce the amount of grease to be filled in, the shield plate 64 isprovided closer to the housing 8c of the constant velocity joint.

The shield plate 64 can be produced by press-forming a steel plate withthe thickness of 1 mm or less, and therefore the hub 4d can be made morelightweight than in the case where the isolation wall 65 (FIGS. 1, 2, 4,5 and 6) is integrally formed on the inner peripheral surface at themiddle portion of the hub 4a which is produced by a forging process asin the first to sixth examples.

In addition, in the present example, the diameter R₃₅ of the inscribingcircle of the heads 35 of the studs 34 to fixedly support the wheel withthe second mount flange 5 is smaller than the diameter D₁ of the axiallyouter end of the outer ring 1 (R₃₅ <D₁), so that the pitch circlediameter of the studs 34 is made as small as possible. In this case, theheads 35 do not interfere with the seal lip 66 of the seal ring 11fixedly fitted into the axially outer end of the outer ring 1. In thisexample, the diameter of the axially outer end of the outer ring 1 ismade smaller, the diameter of the seal lip 66 is made smaller, andtherefore the diameter R₃₅ of the inscribing circle of the heads 35 ofthe studs 34 can be made smaller than in the conventional construction.

The other structure and function are substantially the same to those ofthe sixth example shown in FIG. 6.

Incidentally, omitted from the drawings, the outer peripheral shape ofthe heads of the studs can be formed in a semi-circle shape as in LetterD instead of the circular shape to reduce the pitch circle diameter ofthe studs.

In this case, the cut-out portion of the heads (the straight lineportion of Letter D) is located on the radially inner side closer to theseal lip 66, so that even when the studs are located closer to the innerdiameter side of the second mount flange 5, the heads do not interferewith the seal lip 66.

In all the examples mentioned above, the present application is appliedto the constant velocity joint of the Pzeppe type or the Barfield typeintegral with the rolling bearing unit to rotatably support the vehiclewheel, the present invention, specifically, in the first and secondfeatures, can be applied to the tripod type constant velocity jointwhich is cut off from the rolling bearing unit and provided on thedifferential gear side.

Specifically, the connecting tube for connecting the boot end to the endportion of the housing of the tripod type constant velocity on thedifferential side can take part of the tone wheel. In this case, therotation transmission member is the tripod and the three rollerssupported by the tripod.

When combining the constant velocity joint with the rolling bearingunit, the structure of the rolling bearing unit is not limited to theillustrated examples, and can be applied to various constructionsincluding those of FIGS. 8 and 9.

The tone wheel built-in constant velocity joint of the present inventionconstructed and functioning as mentioned above requires no specialinstallation space for an independent tone wheel, and it is possible todetect the rotational speed at the constant velocity joint section.Therefore, it is possible to combine the constant velocity joint withthe rolling bearing unit having a reduced axial size to detect therotational speed of the vehicle wheel.

What is claimed is:
 1. A tone wheel built-in constant velocity jointcomprising a housing having an open end portion and an inner peripheralsurface formed with an axially long engagement groove or recess, arotatable shaft inserted into the housing and having an outer peripheralsurface, a rotation transmitting member provided between the outerperipheral surface of the rotatable shaft and the engagement groove orrecess of the housing, a connecting tube having a base half portionfixedly fitted onto the opening end portion of the housing and a tiphalf portion projecting axially from the opening end portion, and a bootmade of a resilient material and having one end portion fixedly fittedonto the tip half portion of the connecting tube, and the connectingtube being provided with a detected portion for a tone wheel having acircumferential property changing alternately with a uniform interval.2. A tone wheel built-in constant velocity joint comprising a housinghaving an open end portion and an inner peripheral surface formed withan axially long engagement groove or recess, a rotatable shaft insertedinto the housing and having an outer peripheral surface, a rotationtransmitting member provided between the outer peripheral surface of therotatable shaft and the engagement groove or recess of the housing, aconnecting tube fixedly fitted onto the opening end portion of thehousing and having first and second portions, and a boot made of aresilient material and having one end portion fixedly fitted onto thefirst portion of the connecting tube, the second portion of theconnecting tube projecting from the boot to be provided with a detectedportion for a tone wheel having a circumferential property changingalternately with a uniform interval.